Sound-box



G.A.MOORE SOUND BOX. APPLICATION FILED APR. 3, 1920.

1,375,409, Patented Apr. 19, 1921.

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Orne GEORGE A. MOORE, 0F MEDFoRDpMAsSAcIiUsETTs.

SOUND-BOX.

Specification of Letters Patent. Patented Apr. 19, 1921.

Application filed April 3, 1920. Serial No. 372,377.

To all whom it may concern:

Be it known that I, GEORGE A. MOORE, a citizen of the United States, and a resident of Medford, in the county of Middlesex and Commonwealth of Massachusetts, have invented certain new and useful Improvements in Sound-Boxes, of which the following is a full, clear, and exact specification.

This invention relates to sound boxes for talking machines, and especially .to the means for supporting the. needle arm in order to improve the quality and volume of the tone emitted by the machine.

. As shown in my companion application Serial No. 286571, filed March 31,1919, I pivotally support the needle arm by means of a diaphragm tightly clamped between cross arms composingelements of the needle arm the contacting surfaces of the cross arms and diaphragm being narrowed as much as practically possible. lVhile that narrowing produces good results, I have discovered that I can materially improve the tonal quality and increase the volume thereof by avoiding surface contact of the cross arms between the two screws or rivets by which the cross arms are clamped to-. gether and to the diaphragm. Such spaced contacts are preferably formed by cutting away the intermediate section of each contacting surface of a cross arm, but there are many other ways in which substantially the same results can be produced.

In the drawings forming part of this specification, Figure 1 is a plan view, partly in section, of a sound box embodying my improvements. Fig. 2 is a side sectional view of the same. Fig. 3 is a perspective view of one of the cross arms of the needle arm. Fig. 4 is a detail sectional view of the cross arms and supporting diaphragm. Fig. 5 is a face view of a modified form of the cross arms. Fig. 6 shows another modification. Fig. 7 is a face view of the diaphragm in this latter construction. Fig. 8 is a perspective view of another modification.

The annular case 1 of the sound box is of well known construction, and carries a resonator diaphragm to which is attached an end of the needle arm section 3, the other section 4 having the socket for the reception of the stylus or needle 5. For the pivotal support of this compound needle arm, I provide a diaphragm 6 clamped at its edge by a ring 7 which is peripherally threaded and screwed into a flanged annulus 8, the

former being fastened by screws 9 to a plate 10 integral with or rigidlyattached to the case 1.

Thispivotal diaphragm 6 is thus held at right angles to the resonator diaphragm 2, and with its center in substantially the same plane with the latter.

The means for. attaching the needle arm to the diaphragm 6 comprises across arm 11 connected with the needle arm section 3 by an offset elbow 12, the plate being apertured for the free passage of the section 3. The socket member 4 is likewise provided with a cross arm 13, the two cross arms being fastened to opposite surfaces of the diaphragm 6 by means of screws or rivets 14 both lying in substantially the same plane with the diaphragm 2.

As shown in Figs. 3 and 4, the contacting surfaces of the cross arms 11. and 13 are chanifered 'or reduced to substantially the diameter of the screws'or rivets 14 in order that the flexing of the diaphragm by the vibrations of the needle arm may be hindered as little as possible. While this narrowing of the contact surfaces greatly improves and increases the tone and volume of the sounds emitted from the sound box, I find that I can, still more improveand increase the same, and to a marked degree, by cutting away the portions of the contacting surfaces lying between the screws or rivets 14, as shown in Figs. 1 and 3; or by cutting away still more, so that the screws-14 pass just within the limits of the feet 15, as shown in Fig. 5.

Substantially the same results are produced by substitutingsmall washers 16 for the feet 15, as indicated in Fig. 8,; and also by having the cross arms 11 and 13 straight, and aperturing the diaphragm 6, the diameter of such aperture 17 corresponding to the distance between the feet 15, thus preventing all contact between the cross arms and the pivotal diaphragm except near their ends. r

I am unable to determine the reason for the greatly improved quality and volume re sulting from this comparatively slight change in the pivotal support of the stylus needle arm, but I imagine it arises from the lessened area of the diaphragm which requires to be flexed during the vibrations of the needle arm, and a consequently reduced resistance to such vibrations. At the same time, the feet 15 are so far apart as to insure against yielding of the stylus to any vertical pressure caused by thesupport of the sound box on the record. I am now referring to the type of records having the Where it is attached to the diaphragm in the same straight my line. This insures: that the undulations imparted to the stylus by the record groove shall be accurately imparted to the diaphragm 2, thereby rendering the sounds emitted thereby to be both clearer and stronger.

What I claim is l a p 1. A sound box having a resonator diaphragm, a pivotal diaphragm, a needle arm, a pair of cross members clamping the pivotal diaphragm between them and disposed for the pivotal support of said needle arm, an end of the latter'being attached to the resonatordiaphragm, said parts being so constructed that substantially the ends alone of thecross members contact with the pivotal diaphragm.

2. A sound box having a resonator diaphragm, a pivotal diaphragm, a needle arm attached atone end to the resonator diaphragm, a pair of cross members clamping termediate section of each cross member in contact with the pivotal diaphragm being cut away to permit its terminal sections alone to touch the pivotal diaphragm.

3. A sound box having a resonator diaphragm, a pivotal diaphragm at right angles to the plane of the resonator diaphragm, a needle arm in two sections each having a cross arm, one section being terminally attached to the resonator diaphragm and the other section carrying the stylus, and screws at-the ends of said cross arms tightly clamping them together with the pivotal diaphragm between, said cross arms being arched to present substantially their ends alone in contact with the pivotal diaphragm.

4:. A sound box having aresonator diaphragm, a pivotal diaphragm at right angles to the plane of the resonator diaphragm, a needle arm in two sections each having a cross arm, one section being terminally attached to the resonator diaphragm and the other section carrying the stylus, and screws at the ends of said cross arms tightly clamping them together with the pivotal diaphragm between, said cross arms being arched to present substantially their ends alone in contactwith the pivotal diaphragm, and thesecontacting portions being narrowed to substantially the diameter of the clamping screws.

In testimony that I claim the foregoing invention, I have hereunto set my hand this second day of April, ,1920.

c 7 GEORGE A. MOORE. 

